Diabetes has been identified as an epidemic in the U. S. and is continuing to grow in prevalence, especially type 2 diabetes. In addition, the burden of diabetes, including prevalence and risk of complications, is greater for low-income individuals and minority groups, especially Latinos and African Americans. The Healthy People 2010 report notes that the burden of diabetes can be reduced through secondary and tertiary prevention and facilitating optimal self-management. Few controlled studies have focused on strategies to enhance diabetes self-management in minority or other underserved populations. One approach to increasing our reach and impact is to train nonprofessionals or paraprofessionals to work with multidisciplinary diabetes care teams to support optimal diabetes self-management with minimal added expense. The purpose of this study is to develop, implement, and evaluate the impact of an innovative intervention that combines diabetes self-management education, training, and support with aspects of case management delivered by Medical Assistant Coaches (MACs), to support optimal diabetes self-management (and secondary and tertiary prevention) in low-income minority populations with type 2 diabetes. This efficacy trial compares the Medical Assistant self-management coach (MAC) Intervention with "treatment as usual" (TAU). The target populations will form a total sample of 914 African Americans and Latinos receiving care at five Federally Qualified Health Centers serving low-income individuals in Chicago. The proposed study will use a prospective randomized two-group split-plot repeated measures design. Specifically, it will be a two (treatment groups: TAU, MAC) by four (time: baseline, 6-month, 12-month, 18- month) repeated measures design. The MAC Intervention will be individually tailored based on the Transtheoretical Model and culturally tailored, including Spanish translation where needed. The MAC intervention will be delivered monthly over a one-year period, including both face-to-face contacts during routine primary care visits and regular telephone coaching contacts. The primary outcome variable will be glycemic control measured by HbA1C values. Secondary outcomes include: psychosocial mediators, behavioral outcomes, and short- and longer term biomedical outcomes. If effective in improving glycemic control and/or other measures of diabetes self-management, this intervention has the potential to be easily implemented in other primary care clinics serving minority populations. Furthermore, this intervention has the potential to help contain costs while maximizing our reach and facilitating sustainability.